Portable electric cooking oven



July 13, 1954 R. G. SHEIDLER ET AL 2,683,795

PORTABLE ELECTRIC COOKING OVEN Filed June 13, 1952 6 Sheets-Sheet l Hay.

July 13, 1954 R. G. SHEIDLER ET AL PORTABLE ELECTRIC COOKING OVEN Filed June 13, 1952 6 Sheets-Sheet 2 9 Trama/7 E. (Var/t July 13, 1954 R. G. SHEIDLER ET A1.

PCRTABLE ELECTRIC COOKING OVEN 6 Sheets-Sheet 3 Filed June 13, 1952 w fr J 5 u MMA 3 n ww. a x vw Q:

vr\ A July 13, 1954 R. G. SHE-:IDLER ET AL 2,683,795

PORTABLE ELECTRIC COOKING OVEN Filed June 13, 1952 6 Sheets-Sheet 4 July 13, 1954 R. G. SHEIDLER ET AL PORTABLE ELECTRIC COOKING ovEN 6 Sheets-Sheet 5 Filed June 13, 1952 ,o ||!l\.m W 4 Il il /0/ I \d 0 mi. 2 w/ 1.. v o w 0 H o 5 I e d 9 @w e 8 U M @E @j H July 13, 1954 R. G. SHI-:IDLER ET A1. 2,683,795

PORTABLE ELECTRIC COOKING OVEN Filed June 13, 1952 6 Sheets-Sheet 6 Patented July 13, 1954 PORTABLE ELECTRIC COOKING OVEN Robert G. Sheidler Ohio and Truman B. Clark, Mansiield, Ohio, assignors to Company, Mansfield,

The Tappan Stove Ohio, a corporation of Application June 13, 1952, Serial No. 293,374

1 Claim. 1

This invention relates to electric cooking ovens which are especially adapted for military use in 'transport airplanes when ierrying personnel from place to place. Although the oven was particularly designed for military use it is equally well adapted for civilian use.

1in airplanes the sise and weight oi equipment is of prime importance. Everything must be highly eiicient and as small and light as it is possible to :.naire it without sacricing efficiency. 'th this in mind we designed an electric oven ich is highly efiicient in operation and which is very compact and light in weight, but which is still capable or cooking a large quantity of food the saine time.

As constructed according to our invention the oven comprises a rectangular iront frame of wood or suitable heat insulating plastic and a rear wall of -Wood or suitable plastic which is spaced from the front frame. A rectangular inner sheet instal tubular casing extends between the iront traine and the rear wall with the forward end thereof secured to the inner periphery or the front ne and the rear end thereof secured to the ter periphery ci' the rear wall. The frame, rear wall o tubular casing define an oven chamber ops at the forward end thereof. A door hinged to the front frame in position to close open end oi' the chamber. An outer rectanguar tubular casing which is secured to the outer `eriphery or the iront frame and extends rearardiy therefrom enclcses the inner casing and the rear viali. The rear end to the outer casing is closed by a sheet metal plate which is spaced from the rear wall. The space between the inner and outer casings and behind the rear wall is filled with suitable insulating material. The outer casing also encloses an upper compartment above the oven chamber.

A plurality of vertically spaced trays are removably mounted in the oven chamber upon suitable tracks which are secured to the sides of the inner casing and extend freni the front to the rear ci the chamber. rfhe tracks, intermediate the ends thereof, are spaced from the sides of the inner casing to permit the upward now of vapor. Each tray has incorporated therein an electric resistance heating element which is connected to suitable plugs carriecl by the tray and which engage suitable outlet sockets mounted in the rear wall when the tray in place. The energization of the heating element is controlled by a standard electric switch which is constructed to be manually closed and automatically opened by a thermally responsive element which is subject to the temperature of the oven chamber.

In airplanes it is essential that no vapors, which might condense on and befog the control instruments, be allowed to escape into the airplane. To this end we provide a substantially vapor tight condenser in the upper compartment which connected to the upper end of the oven chamber by a vertical conduit. The condenser is in the form of an elongated closed removable recep'acle having a plurality of spaced transverse baies therein. During use vapors created. in the oven will flow up through the conduit into the corrdenser and condense on the balies. The con-- denser shouldbe remove(n and emptied after each use or" the oven to insure maximum efficiency thereof.

An indicating mechanism is also moun the upper compartment in position to be through a window in the iront wall oi per compartment. By this indicating mechanism one can tell at a glance how long food in the oven chamber has been cooking, how long it will be until the lood is properly cooked, and how long' the food has been properly cooked. The indicau tor is set in operation by the manual closing oi the control switch.

The oven is adapted to simultaneously cool; a great variety of dierent foods or combinations of food. In use the different foods are put in separate containers which are placed upon the trays in the oven chamber. The control s 'tch is then closed by the manual actuation oi a lever which extends out through a slot in the front wall of the upper compartment. The actuation or this lever in closing the control switch also sets the indicator mechanism in operation. When the temperature in the oven chamber reaches a predetermined degree in accordance with the setting of the control switch the control switch is automatically opened by the thermally responsive element vwhich is operatively connected. to the control switch. But although the heating elements have been cle-energized by the opening of the control switch the food. in the oven will continue to cool; until properly it is be understood that the different foods being cooked at the same time must be carefully lected so that all will require the saine cooking time at the saine temperature. such coinbinations of food are possible.

The principal object of the invention is to pro'- vide a small compact light weight electric ccoring oven which is highly efficient and is capable of simultaneously cooking a large quantity of the same or different foods.

Another object of the invention to provcle in an oven of the aforesaid character means to condense all vapors being generated therein dur ing use.

Another object of the invention is to provide an oven of the aforesaid type having an indicating and control mechanism incorporated therein by which one can tell at a glance how long food in the oven has been cooking, how long it will be until the food is properly cooked, and how long the food has been properly cooked.

Other and more limited objects of the invention will be apparent from the following specification and the accompanying drawings forming a part thereof wherein:

Fig. l is a vertical section from the front to the back of an oven constructed according to our invention, the plane of the section being indicated by the line l-l on Fig.

Fig. 2 is a horizontal section taken on the line 2--2 of Fig. l;

Fig. 3 is a vertical transverse section taken on the line 3 3 of Figs. 1 and 5;

Fig. 4 is a fragmentary vertical section taken on the line A-t of Fig. 5;

Fig. 5 is a horizontal section taken on the line 5 5 of Fig. l;

Fig. 6 is a fragmentary front elevation of the upper portion of the oven shown in Figs. l to 5;

Fig. 7 is an enlarged plan view of the indicating mechanism removed from the oven showing the various parts thereof in inoperative position;

Fig. 8 is a View similar to Fig. 7 showing the various parts of the indicating mechanism in operative position;

Fig. 9 is a side elevation of the indicating mechanism as viewed from the left of Fig. 7;

Fig. 10 is a vertical section taken substantially on the line lil-Hl of Fig. '7; and

Fig. 1l is a detail section on the line ll-il of Fig. 7.

Referring now to the drawings by reference characters the numeral i indicates generally an electric cooking oven constructed according to our invention. The oven l comprises a rectangular front frame 2 and a rectangular rear wall 3 which are made of wood or suitable heat insulating plastic material. A sheet metal inner tubular casing l having the top wall 5, the botw tom wall il and the side walls l and 8 extends between the front frame 2 and the rear wall 3y which is open at the forward end thereof. A door i2 is secured to the front frame 2 in position to close the oven chamber Il by hinge means $3. Latching means lll is provided to hold the door i2 tightly closed. The door i2 comprises the spaced inner and outer walls i5 and l which are connected together by the peripheral wall I1. The space between the inner and outer walls is packed with heat insulating material i8. ln order to insure the oven chamber ll being vapor tight when the door l2 is closed a suitable gasket, against which the door l2 closes, is provided around the open end of the oven chamber il. An outer tubular casing i9 having the top wall 2c, the bottom wall 2i and the side walls 22 and 23 which is secured to and extends rearwardly from the front frame 2 encloses the inner casin l and the rear wall 3. The bottom and side walls of the outer tubular casing i9 are permanently secured to the bottom and sides of the frame 2 CTI The frame 2, rear wall 3, and the inner casing i denne an oven chamber li and the top wall thereof is disposed above the top of the frame 2. The rear end of the outer casing I9 is closed by a sheet metal plate 24 which is spaced from the rear wall t. lThe forward end of the outer casing above the frame 2 is closed by a panel 25 which extends upwardly from the top of the frame 2. A sheet metal partition 25 which is secured to and extends rearwardly from the top of the frame 2 within the outer casing i9 provides an upper compartment 2l above the oven chamber ll within the outer casing i9. The space between the outer casing i9 and the inner casing d below the partition 2% is packed with insulating material 25 similar to the insulating material i8 in the door l2.

A plurality of supporting trays generally indicated by the numeral 39 are removably mounted in the oven chamber il in vertical spaced relation to each other upon tracks 3i which are permanently secured at the ends thereof to the side walls 7 and E. The tracks 3l, between the ends thereof, are spaced from the side walls 'i and 8 as shown at 32 to permit the upward now of vapors generated in the oven chamber li during use. Each tray Sil comprises two rectangular sheet metal plates 33 and te welded together. A zig-zag groove 35, the top of which is closed by the top plate 33, is formed in the bottom plate 3d. A pair of loncr unbroken helical electrical resistance heating elements 35 are embedded in suitable heat conducting electric insulating material in the groove 35. The ends of the heating elements 36 are connected to electric connector plugs 3l, which are carried by the trays 30 at the inner end thereof adjacent each side thereof. The plugs 3l' carry prongs 38 which enter into electric outlet sockets 59 mounted in the back wall 3. The heating elements 35, when energized, heat the trays Se which in turn heat the air in the oven chamber il and any utensils on the trays The energization of the heating elements 3e is controlled by switching means which is disposed in a pocket il between the top wall 5 of the chamber il and the partition 2t. The switching means lli? includes a cam shaft l2 having an arm i3 secured to the upper end thereof. The switching means f is adapted to be manually closed by rotating the cam shaft i2 through approximately with the arm 133; and to be automatically opened, when the temperature in the oven chamber reaches a predetermined degree, by a thermally responsive element ld which is subject to the temperature in the oven chamber and is operatively connected to the switching means lill. After each actuation a spring d5 returns the cam shaft [l2 to initial position. The switching means Bil which may be adjusted to be opened at any desired temperature of the oven chamber Il must be again manually closed after each automatic opening thereof by the thermally responsive element Switching means of this general type is available in the open market. Consequently it is thought unnecessary to show and describe this switching means more in detail herein.

In order to prevent the escape of vapors, which are generated during use, from the oven chamber il, we provide a substantially vapor tight condenser generally indicated by the numeral 5d which is removably mounted in the upper compartment 2l. The condenser 5G comprises an elongated receptacle El which is rectangular in cross section and is closed by a removable cover 52. A plurality of longitudinally spaced baiiies 53 extend from side to side of the receptacle 50 and from the cover 52 downwardly with the lower edges thereof spaced from the bottom of the receptacle. The bailies 53 are permanently secured to the sides of the receptacle 5|. The condenser 50 is slidably supported upon a pair of guide rails 54 and is removable from the upper compartment 21 through an opening 55 in the front panel 25. When the condenser 50 is in place within the compartment 21 the opening 55 is closed by a cover plate 5B which is permanently secured to and spaced from the front wall of the receptacle 5| by a pair of connecting links 51. A latch 58 carried by the cover plate 55 holds the condenser 50 in place within the compartment 21. vapors generated in the oven cha-mber II during use flow up from the top of the chamber II through a conduit 59 and into the condenser 50 through an aperture 60 in the rear wall thereof. tongue 6I which is integral with and extends upwardly from the rear wall 3 into the compartment 21 behind the condenser 50. A flexible coupling 62 carried by the tongue 6| connects the upper end of the conduit 59 with the entrance aperture in the condenser. Hot vapors flowing from the oven chamber I into the condenser 59 condense upon the bales 53 and the walls of the receptacle I and drip down into the bottom of the receptacle. The condenser 50 should be removed after each use of the oven and the liquid condensed therein emptied out through the aperture Eil in order to insure maximum efficiency of the condenser each time the oven is used. A spring finger 63 carried by the upper end of the tongue 6l holds the rear end of the condenser in place.

In order that an attendant may always know how long a time food in the oven chamber I I has been cookingl and how long a time it will be until the food in the oven is properly cooked we provide an indicating mechanism for visually indicating these periods of time. After the food is properly cooked the indicating mechanism 10 will also indicate how long a time it has been properly cooked. The indicating mechanism 19 is disi posed within the compartment 21 and is carried by a closure plate 1I which is removably secured es by screws 12 to the front panel 25 in front of an opening 13 through which the indicating mechanism 'i9 is inserted into and withdrawn from the compartment 21. The plate 1| has a window 14 therein which is closed by a small pane of clear glass having indicia 16 thereon.

The indicating mechanism 10 comprises a horizontally disposed base plate 80 having the vertical legs 8| and 82 by which the base plate 80 is secured to the closure plate 1 I. The base plate 59 has a pivot stud 83 secured thereto and extending downwardly from the underside thereof. A circular disc 84 and a lever 85 are pivotally mounted upon the stud 83 and are retained thereon by a nut 86. The forward end of the lever 85 extends out from the compartment 21 through an elongated horizontal slot 81 in the closure plate 1|. The rear end of the lever 85 beyond the base plate 1I has a boss 88 on the underside thereof through which a screw 89 is threaded. An ear 90 extends rearwardly from the leg 8| and an ear 9| extends rearwardly from the leg 82. The lower edges of the ears 90 and 9| are spaced from the base plate 80 as shown at 92, and the inner edge of the ear 9| is cut away as shown at 93 to accommodate a vertical arcuate sheet metal shutter 94. An arcuate col- The conduit 59 is formed in a ored glass plate 95 is carried by a-nd between the ears and 9|. The plate 95 is preferably contrastingly colored, the right hand half 96 thereof being one color, for example red, and the left hand half 91 thereof being another color, for example green.

The shutter 94 is disposed between the colored glass plate 95 and the clear glass plate 15 behind the window 14, and is carried by a horizontally disposed swinging sheet metal plate |00 which is pivotally mounted upon a pivot stud |0I which is secured to and extends upwardly from the base plate 80. The swinging plate |09 has an elongated arcuate slot |02 therein. The centers of curvature of the shutter 94, the colored glass 95, and the elongated slot |02 are all in the axis of the pivot stud IUI. A spring motor |03 of standard construction is mounted in a casing |04 which is disposed above the swinging plate |02 and is secured to the base plate 80 by bosses |05 which extend downwardly from the casing |04 through the arcuate slot |02 to the base plate 80. The spring motor |0-3 drives a shaft |05 which extends downwardly from the casing |04 and has an elongated gear |01 secured thereto. The spring motor |03 includes an escape mechanism (not shown) which controls the speed of rotation of the shaft |05 and gear 'I and limits it to approximately one and one-half revolutions per hour. The gear |01 extends down through the elongated slot |02 in the swinging plate |00 and an aperture |08 in the base plate 80, and meshes with a concave arcuate rack |09 formed in one edge of the slot |02, and with a segmental gear section I I0' formed in the edge of the disc 84. The disc 84 has a stud III secured thereto and extending downwardly therefrom in position to be engaged by one side of the lever 85, and diametrically opposite the gear section I I0 the disc 84 has a segmental recess I I2 in the periphery thereof.

A snap type switch |I5 having the terminals I It is removably secured by bolts I I1 to a bracket I|8 which is bolted to the base plate 80 by bolts I I9 and extends upwardly therefrom. The switch ||5 includes an actuating lever |20 which extends down into the recess ||2 in the disc 84 in position to be alternately engaged by the edges |2I and |22 at opposite sides of the recess |I2. An electric light bulb |23, the energization of which is controlled by the switch I5, is mounted in position to project light through the colored glass plate 95 and the window 14 when energized.

To initiate operation of the oven the lever 95 is manually rotated clockwise about its pivot 83 from the position shown in full lines in Figs. 5 and '1 to the position shown in` dotted lines in Fig. 5 and full lines in Fig. 8. As the lever 85 approaches the end of its movement in this direction the screw 89 carried thereby engages the arm 43 on the control switch shaft 42 and rotates the shaft 42 through approximately 90 which closes the switch 40 and energizes the electric resistance heating elements 36 in the trays 30. During this movement of the lever 85 the lever 85 also engages the stud I|| carried by the disc 84 and rotates the disc 84 through approximately 60 in a clockwise direction from the position shown in Figs. 5 and '1 to slightly beyond the position shown in Fig. 8. At the end of its movement in this direction the edge |2| of the recess ||2 in the disc 84 engages the switch lever |20 and moves it from the position shown in Fig. '1 to the position shown in Fig. 8 which closes the switch II5 and energizes the bulb |23. The

rotation of the disc 84 in a clockwise direction by the lever 84 will rotate the gear H31 through the segmental gear section H9 a plurality of turns in a counterclockwise direction which will wind up the spring motor |613. The rotation of the gear lill by the segmental gear on the disc B also shifts the swingingplate H10, through the rack |99, from the position shown in Figs. and 7 to a position slightly beyond that shown in Fig. 8. The shifting of the swinging plate it?! removes the shutter 9d carried thereby from between the colored glass plate 95 and the Window EL3 so that light from the bulb |23 is projected through the plate 95 and window 14. The control switch i is now closed and the indicating mechanism 'l is set for operation. The lever 85 is then released and a spring |25 returns it to its initial position. The spring motor |33 now rotates the gear |67 in a clockwise direction which slowly returns the disc 84, the swinging plate |98 and the shutter 94 carried thereby, to their original positions as shown in Figs. 5 and 7. The adjustment of the mechanism is such that this return movement takes approximately one hour; and the adjustment of the thermally responsive element 4 is such that food in the oven chamber ii will be properly cooked in approximately one-half hour. As the shutter 94 returns to its initial position it gradually cuts ol the light being projected through the window 94, and the leading edge |26 thereof registers with the indicia 78 on the window pane 75. As long as 1coth red and green lights are visible through the window 14 one knows that food in the oven chamber Il is not yet completely cocked and the position of the leading edge |26 of the shutter 913 with respect to the indicia 78 will indicate how long the food has been cooking and how long it will be until the food is completely cooked. When green light alone is visible through the window 7d one knows that the food has been completely cooked, and the position of the leading edge |26 of the shutter Sd with respect to the indicia 78 will indicate how long the food has been completely cooked. For example, assume that the edge of the shutter 94 registers rst with the line A of the indicia '1B and then with the line B thereof. When the edge |26 is in register with the line A both red and green iight will be visible which indicates that the food is not yet completely cooked and the position of the edge |25 shows that the food has been cooking for fifteen minutes and that it will be fifteen minutes more until the food is completely cooked. When the edge |25 is in register with the line B green light alone will be visible through the window 7d which indicates that the food is completely cooked, and the position of the edge |26 shows that the food has been completely cooked for fifteen minutes.

As the disc 84 approaches its initial position the edge |22 will engage to switch lever |20 and shift it from the position shown in Fig. 8 to the position shown in Fig. 7 thus opening the switch I5 and deenergizing the bulb |23.

While the indicating and control mechanism shown and described herein is particularly adapt- -ed for use with the oven shown and described, it per se forms no part of the present invention, but constitutes the subject matter of our copending application Serial No. 293,375 led June 13, 1952.

The outside dimensions or the oven i shown herein are approximately 141/2 inches deep, 12 inches wide and 16 inches high; and the oven chamber is approximately 111/2 inches deep, 9% inches wide, and 10 inches high. But not withstanding its small size the oven is capable of simultaneously cooking six selected complete meals, each of which consists of ve different foods, in one-half hour without any vapors generated during use escaping from the oven.

From the foregoing it will be apparent to those skilled in this art that we have provided a very simple and efficient mechanism for accomplishing the objects of the invention.

It is to be understood that we are not limited to the specic construction shown and described herein as various modifications may be made therein within the scope of the appended claim.

What is claimed is:

A portable vapor tight electric cooking oven comprising a plurality of walls and a door defining a vapor tight cooking chamber and an upper compartment thereabove which is separate from said cooking chamber, a substantially vapor tight condenser removably mounted in said upper compartment, means deiining a conduit between the Lipper end of said cooking chamber and said substantially Vapor tight condenser through which vapor escapes from said cooking chamber into said substantially vapor tight condenser, a plurality of imperforate trays removably mounted in said cooking chamber in vertically spaced relation with the peripheral edges thereof spaced from the boundary walls of said cooking chamber and said door to provide uninterrupted paths for the upward flow of vapors, and an electrical resistance heating element ncorporated in each of said trays.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,118,454 Weeks Nov. 24, 1914 1,178,299 Berry Apr. 4, 1916 2,389,197 Rutenber Jan. 11, 1944 2,472,818 Gardes June 14, 1949 2,556,450 Schulze June 12, 1951 2,556,597 Pierson June 12, 1951 

